Collision gas-discharge laser utilizing europium vapor. I. Observation of self-terminating oscillations and transition from cyclic to quasicontinuous operation

The requirements which active media of cw atomic collision lasers must satisfy were formulated on the basis of an analysis of earlier investigations of other workers and the present authors. It was concluded that the promising media were elements with a partly filled 4ƒ shell (rare-earth metals). Several stimulated emission lines of ionized europium were observed in the visible and near infrared range. The majority of these lines was obtained at anomalously high (above 200 mm Hg) helium pressures. The principal properties of laser radiation were determined. A continuous transition from self-terminating oscillation to quasicontinuous emission was achieved for one of the lines by increasing helium pressure.